The present invention relates generally to a cleated shoe or a shoe having cleats in use for track and field, soccer, rugby, baseball, golf, or the like. More specifically, the present invention pertains to an improvement in a sole structure of a cleated shoe for the purpose of advanced traction performance due to an improved fittability between a sole and a plantar surface of a foot and also for the purpose of dispersion of thrust from the cleats.
In cleated shoes for track and field, various kinds of tightening means such as belts, shoelaces, or the like have been used in order to tightly fasten a shoe to a foot of a shoe wearer. In such shoes, a tightening means such as belts or shoelaces presses a foot of a shoe wearer via an upper of a shoe against an outsole.
An outsole of such cleated shoes is generally formed to conform to the shape of a foot in the longitudinal direction, but not in the transverse direction. However, especially, a forefoot portion of a foot also has an undulation in the transverse direction. Therefore, in a prior art shoe, even when fastening a tightening means, a plantar surface of a forefoot portion of a foot cannot be closely contacted with the outsole. Also, a region where a force is applied during running is not the whole plantar surface of a forefoot portion but a part of the plantar surface of the forefoot portion. Unless such a part of the plantar surface is closely contacted with the outsole, a slippage may occur between the plantar surface of a foot and the outsole of a shoe during running. Thereby, a gripping force of a foot relative to the ground through the outsole cannot be securely transmitted to the ground, which results in decrease in traction of a shoe.
A Japanese patent application laying-open publication No. 10-42904 discloses a shoe sole in use for bicycle races. This shoe sole has concave portions formed therein at positions that conform to a thenar and hypothenar eminence of a foot of a shoe wearer, respectively. The said publication describes that maintaining a thenar and hypothenar eminence of a foot in the corresponding concave portions of a shoe sole enables stepping force of a foot to instantly transmit to a pedal of a bicycle.
In a bicycle race, an athlete pushes a pedal by his or her entire foot without flexing the foot with a portion of a sole surface of a shoe contacted to the pedal. In contrast, in the case of track sports, an athlete must grip the ground surface securely at the time of striking onto the ground and advance forward by kicking the ground surface at the time of leaving the ground, which requires traction at the time of flexing of the forefoot portion of a foot.
Furthermore, in the case of track shoes, a strong thrust from the cleats during running acts upon a plantar surface of a foot. Therefore, in a prior-art cleated track shoe, an effective countermeasure is needed that can not only improve traction performance but also efficiently tolerate thrust from the cleats.
An object of the present invention is to provide a sole structure for a cleated shoe that can improve traction performance through the advanced fittability between a sole and a plantar surface of a foot and that can disperse thrust from cleats.